Re: Have any PRs in the last week or so touched objects that are followed by ResourceTracker

Not sure why this is suddenly happening now and only on the NumPy nightly
wheels, but it migbt be relevant that this warning was seen as a bug by
upstream and they made the resource_tracker reentrant-safe:
https://github.com/python/cpython/issues/131788

This is merged in `main`, backported to 3.13 and released in 3.13.7, but
has not yet been backported to 3.14 because that branch is in the RC freeze.

I happened to know about this because it caused some breakage in joblib,
but that’s been fixed for a month or so.

On Mon, Sep 22, 2025 at 8:05 PM Andrew Nelson via NumPy-Discussion <
[email protected]> wrote:

> Hi all,
> in the last few weeks have there been any PRs that have touched objects
> that are followed by the Python ResourceTracker. I'm talking about things
> like Locks, semaphores, mutexes, etc?
>
> I'm seeing some weird behaviour in scipy CI where a test (
> https://github.com/scipy/scipy/blob/main/scipy/optimize/tests/test_optimize.py#L3442)
> that uses an object that wraps `multiprocessing.Pool` has started giving
> test fails. A typical log (
> https://github.com/scipy/scipy/actions/runs/17925659616/job/50971069339#step:12:1229)
> has text like:
>
> "multiprocessing.resource_tracker.ReentrantCallError: Reentrant call into
> the multiprocessing resource tracker"
>  and
> "UserWarning: ResourceTracker called reentrantly for resource cleanup,
> which is unsupported. The semaphore object '/mp-380ciby1' might leak."
>
> In my investigations (https://github.com/andyfaff/scipy/pull/83) it only
> seems to happen for cp312 and the numpy nightly wheel. It doesn't seem to
> trigger for cp312+np2.3.3 or for cp311.
>
> Given that it only seems to happen with the numpy nightly wheel I'm
> wondering if it's therefore a numpy issue. As far as I can tell it's
> started happening in the last five days or so.
>
>
> --
> _____________________________________
> Dr. Andrew Nelson
>
>
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